The present invention relates to a liquid crystal display device and, more particularly, to a liquid crystal display device having a liquid crystal cell and an integrated circuit semiconductor chip for driving the cell mounted on one of a pair of substrates forming the cell.
In the conventional type liquid crystal display device with a driving integrated circuit chip mounted on one of substrates forming a liquid crystal display cell, the liquid crystal display device has the construction in which metal films are formed and patterned for electrical wiring on one of the substrates constituting the cell and a driving integrated circuit semiconductor chip which shall be hereinafter referred to as an LSI chip is bonded directly on patterned metal film as shown in FIG. 1. The liquid crystal display cell 1 comprises a lower substrate 2 and an upper substrate 4 both of which are made of transparent glass or other like material, with transparent electroconductive electrodes 9 and 10, respectively formed on the inner surfaces thereof, and arranged substantially parallel to each other with a predetermined spacing, for example, 5 to 15 .mu.m, and sealed at the periphery with a sealing member 3 such as frit glass or an organic adhesive, and a nematic liquid crystal 11 sandwiched therebetween. Multilayer metal film wiring 12 including a metal film layer having good wettability with solder is formed on the lower substrate 2 and an LSI chip 6 is mechanically and electrically bonded on the multilayer metal film wiring 12 via solder 5, and the LSI chip 6 and multilayer metal film wiring 12 are covered with epoxy resin 7 and resin 8 for filling up pinholes in the epoxy resin 7 to be protected from external environments as proposed in co-pending Japanese Application No. SHO 59-76480.
Under highly humid environmental conditions, the above-mentioned type liquid crystal display device sometimes resulted in failures to display because disconnections of metal film wiring due to corrosion or electrochemical reaction, or short-circuits between the metal film wirings due to separated metals on operating condition, resulting from forming of a water film between adjacent metal film wirings caused by water absorption of resin coatings 7 and 8 and from peeling-off of resin coatings 7 and 8 from the substrate 2. As a solution to the above problem it is proposed to cover the metal film wiring 12 with inorganic material film in the above-mentioned Japanese Patent Application No. SHO 59-76480. This has ensured reliability under sever environmental conditions, but it increases the time and cost of production when a sputtering technique is adopted.